Zetsu is a member of the Akatsuki. He is a goofy-ass plant man who's the most racist, sexist, and homophobic member in the Akatsuki. He makes fun of Sasori on a daily basis because of his femboy nature and thinks that OMORI the Shame is cringe; that's how he got his only friend, Eiko Hayashi (makes sense because they're both dumbasses). He is teaching her the ways of racism.
Zetsu is 2 people in one body: one being White Zetsu and the stronger Black Zetsu. Zetsu enjoys torturing innocent bugs and flies because his Piranha Plant-looking ass needs to eat. He has caused many incidents with the other members of the Akatsuki and has nearly caused the death of Sasori almost 7 times. He's probably the only guy in the team that doesn't give a flying fuck about Midbidi Toilet, as he knew it could've been worse, like people making articles about memes that are basically cropped pornography. Instead, he focuses on one thing: harassing people for no reason.
He's a Hamtaro (anime series) addict and would sell things for more DVDs of the anime, like Sasori's Miku body pillows and Hidan's copies of "Boats and Hoes". He likes making fun of Sasori's relationship with Deidara because, unlike them, he's a real Sigma Rizzler in Ohio. He frequently tries to make Konan do the Paper Shaker, but it always fails. Nobody can trust Zetsu because of the shit he says, and as such, people need to watch over him so another incident doesn't happen.
People always wonder why he's friends with Eiko Hayashi, a literal nine-year-old, and it's simple: not because he's looking for a cupcake, but because he has no friends and he hates MIDMORI, and because he thinks 2+2=9, this would lead him to become friends with all the dumbasses in UnAnything like Cirno and frequently makes fun of Hidan for not being able to be in the Seven Deadly Sines. He is the rival of PETA as he hates animals and is a plant. He was denied from joining the Hank Gang as he was too offensive for them, so now he goes around teaching Eiko Hayashi the ways of the Biden Blast.